1. Field of the Invention
The present invention relates to vibrators, and in particular to unidirectional impact vibrators of the pneumatic type.
2. Prior Art
Impact vibrators employing a pneumatically actuated piston have found wide use in industry for knocking off accumulations on electrostatic precipitator plates and wires, for deslagging boilers, knocking dust or other accumulations off of surfaces such as in bin hopper applications, and the like. A representative example of such vibrators may be seen depicted in U.S. Pat. No. 3,731,907 entitled "Vibrator System" and issued to Lash.
With reference to FIG. 1, typically such vibrator assemblies as assembly 12 depicted therein are employed as a vibrator-rod assembly 10 wherein the vibrator assembly 12 is interconnected by means of a tapered sleeve mount 34 to a tapered end 36 of an elongate rod member 14, the distal end of which is in turn inserted in a rod socket 16 which is integrally attached to an anvil 18 which is to be vibrated. The anvil 18 will also typically have, in the application depicted, a plurality of precipitator plates 20 or the like which, in a given plant process, may have accumulated thereon undesirable deposits which must be vibrated free.
In operation of the vibrator-rod assembly 10, a source of pressurized fluid is introduced into a pneumatic port 11 into the piston chamber or annulus of the vibrator body 22. Referring more particularly to the vibrator assembly 12 itself, such assemblies will be conventionally comprised of the body 22 forming the aforementioned annulus in which a piston (not shown) vibrates up and down in response to the charge from the port 11. The annulus is sealed above the piston by means of a cap 24 which is interconnected to the body 22 by means of bolts 26. In like manner, the tapered mount 34 having a lower base plate 30 is interconnected to an upper base plate 28 by means of bolts 32. The mount 34 includes a tapered sleeve therein which matingly engages a corresponding tapered end 36 of the rod member 14. It is conventional to provide such a mount 34 - body 22 assembly in a two piece construction whereby the mount 34 may be conveniently replaced with another mount having a different taper adapted to receive the tapered end 36 of the particular rod member 14 encountered in a given application.
Once the vibrator assembly 12 has been operating for a short period of time the press fit between the internal bore of the mount 34 and the end 36 will be such that little if any relative rotational movement in the direction of arrow 13 will be experienced between rod member 14 and mount 34 due to the tremendous longitudinal forces exerted upon the rod 14 by the vibrator assembly 12.
A very serious problem has been experienced with the particular vibrator construction of FIG. 1. Whereas the primary force generated by the vibrator 12 and transmitted through rod member 14 to anvil 18 is in the downward direction, it has been found that there is frequently also a torsional component of force transmitted from the vibrator 12 through rod 14 often of a magnitude such that over a period of prolonged use damage occurs to the vibrator-rod assembly 10 in the vicinity of the rod socket 16, either by the socket 16 itself breaking free of the anvil 18, or the like. It has been thought that this phenomenon may be due to a rotational force imparted upon the vibrator assembly 12 by the pressurized fluid injected therein at the pneumatic port 11.
Not only has damage been encountered in the area adjacent rod socket 16, but it has also been found that damage occurs at the interface between base plates 28 and 30, either by way of bolts 32 fatiguing, or shearing, deterioration of gaskets and seals between the plates, or the like.
Accordingly, numerous attempts have been made to overcome these problems. One such approach has been to provide a one piece construction such as that depicted in the aforementioned U.S. Pat. No. 3,731,907. However, such construction while alleviating problems at the situs of the base plate interface nevertheless did not attack the fundamental problem in that torsional forces were still being transmitted from the vibrator assembly 12 to the rod member 14 or any other article attached to the mount 34. In many applications the resulting necessary repairs could become extremely expensive and time consuming involving the total shut down of processing plants while rod members or sockets are replaced or repaired and the like.
Yet another problem in the installation of such vibrator assemblies 12, is that due to the weight and taper thereof, once the assembly 12 is placed upon a rod member 14, it is extremely difficult and cumbersome to rotate the vibrator assembly 12 about the longitudinal axis of rod 14 and assembly 12. Such deficiency frequently becomes troublesome in installations and repair due to limitations on length and positioning of the pneumatic tubes connecting to the port 11. For example, it may be desirable to rotate the vibrator assembly 12 to a position where the connector to the pneumatic port 11 may be more readily accessible for repair of the assembly 12, for routing shorter pneumatic tubes to the port 11, or the like. Yet, in conventional designs once the assembly 12 was positioned on the workpiece, such re-positioning was rendered extremely difficult if not impossible.
Still a further serious problem associated with vibrator assemblies of a conventional design is that a great deal of the energy developed by the piston which is intended to be transferred to the article to be vibrated is lost in the housing or body of the vibrator assembly itself. This was thought to be due, in part, to the fact that the piston was typically made to impact directly against an internal portion of the vibrator body itself which absorbed much of the energy.
The housing was, in turn, attached to a mounting means which mounted the vibrator to the article to be vibrated. Thus, while vibrating energy was transferred from the housing or body through the mount to the article, much of the initial energy of the piston was lost in the mass of the body, as aforesaid. Thus, a vibrator design was long sought after which could effect more efficient energy transfer from the piston to the article itself.